设数列{an}的前n项和为Sn,已知S1=1,Sn+1/Sn=n+c/n (c为常数,c≠1,n∈N*)且a1,a2,a
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An=a1b1=a1b2+...+anbn有误应是An=a1b1+a2b2+...+anbn
An+3B2n
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